Oracle Blog

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Monday Sep 24, 2007

I finally launched my LOC Vulcanite rocket for the first time. The results
were outstanding.

I blogged about my
Vulcanite earlier this year. This rocket is 53" tall
(4.5 ft, 135 cm) and weighs 32 oz (2 pounds, about 1 kg) before adding a motor.
I painted it orange and black to make it more visible against blue sky or
light clouds.

On the day I first launched it, I achieved (1), (2) and (3). The first launch,
and L1 certification attempt, was on an AeroTech H73J. This motor weighs 10
ounces when ready for launch, and is about 6" (15 cm) long. It provides 16
pounds of force at liftoff, sufficient to launch this rocket easily, but not
so much that I have far to walk if it decides to become a "cruise missile" by
turning and flying horizontally.

The results were gratifying.

(When I take pictures of a launch,
I press the shutter as soon as I see any vertical movement, which
resulted in a well-composed picture. At least it did this time...)

According to the on-board altimeter I added, it flew to 1,584 feet (480 m).
More importantly, it flew almost perfectly straight up, and the 24-inch
parachute returned it safely to Earth not far away from the launch rail.
However, it seems that the delay I chose - the time before the parachute
is ejected - was not long enough. With the correct delay, the rocket
would have flown higher.

Beaming with success, I decided that the next launch would begin to test
the limits of this rocket. I chose an I218R - an 8-inch (20 cm) motor with
almost twice the total impulse of the previous motor. (Think of total impulse
as the total force exerted while the motor is burning.) Even though I knew
it would fly much higher, the wind was very light that day, so I
didn't expect to walk far to recover it.

With this motor, the Vulcanite flew to 4,469 feet (1.35 km)! Also impressive
was its maximum speed: over 500 MPH (800 km/h). You can see that in the picture
to the right: I have an itchy shutter finger, but the rocket launched so fast
I missed it entirely!

Unfortunately, although the nose cone ejected properly, the parachute never came
out. The two ends of the rocket, connected by an elastic cord, fell over 4,000 feet to the
ground. Fortunately, the launch area was an empty corn field with large clods of
dirt which had been softened by rain the day before. The only damage was a partial crack
in one plywood fin. A little sanding, some new epoxy, and it should fly again.